Origin and Evolution
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Living systems evolved from original independent cells into complex higher-level organisms, which then evolved into still higher-level superorganisms. At each transition, a common sequence of behavioral changes took place, eventually producing cooperation and aggregation into a higher-level entity. The result was a three-level hierarchy of interdependent and mutually supportive living systems.


Sequence of Behavioral Changes
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Living organisms have undergone a long evolution from single-cell microorganisms, to complex multi-cell organisms, to multi-organism superorganisms. In reviewing studies of this progression to higher levels of complexity, a common sequence of behavioral characteristics can be observed:
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This same sequence has taken place as individual cells joined to produce organisms, and again as individual organisms joined to produce superorganisms.

      ExistenceProliferation
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The first living systems were individual, independent, self-sufficient cells, similar to bacteria. They lived in, and were adapted to, a particular nurturing environment, where each cell could readily obtain the nourishment it needed. As they lived and reproduced, the population of cells increased to populate the physical area where their unique nurturing environment existed. Increased population provided greater opportunities for species survival.

      ProliferationCompetition
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As they continued to reproduce, the cell population began to reach the limits of its environmental niche's ability to meet their increasing demands for more and more nutrients and energy. Eventually they were faced with a scarcity of resources. Through their change-inducing reproduction process, some new cells were better able to compete for food and energy, and survived to reproduce better than the others. Competition produced cells more capable of surviving environmental changes.

      CompetitionCooperation
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Over time, natural selection of the most effective design variations led to a variety of new, more-capable and complex cells with improved capabilities for interacting with their external environments, which now included a proliferation of other cells. As the variety and complexity of cells continued to increase, some cells with complementary specialized capabilities began to interact with each other for mutual benefit. Cooperative cells together gained a competitive edge in acquiring nutrients and providing protection.

      CooperationAggregation
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As interdependent cell behavior became more successful, the cooperative cells became more and more tightly integrated into a new kind of living entity. Within that aggregation structure, the highly organized and constrained behavior of its component cells caused the emergence of a new higher-level organism with its own unique life-function properties. The organism structure provided a nurturing and protective internal environment for its aggregated cells, offering better opportunities for their species' survival than individual cells acting alone.
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The emerging organisms became complete and independent living systems, whose limited life cycles included a change-inducing reproduction processes. The result was a mutually dependent coevolution that improved the survival capabilities of both cells and organisms.
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Increasing Levels of Complexity
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As independent living systems, early organisms existed in physical environments, from which they ingested raw materials for nourishment and energy. As they reproduced to fill their local environments, individual organisms went through the same sequence of behavior cycle as the original cells, from existence to aggregation.
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Organisms with different capabilities emerged through the variations caused by their change-inducing reproduction process and natural selection. Some organisms with complementary capabilities learned to interact cooperatively for greater mutual benefit and higher survival ability. Over time, as they began to merge into superorganisms, the individual organisms became dedicated to the specialized cooperative behavior required to produce the superorganism's various life functions.
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Like cells and organisms before them, some superorganisms evolved to become fully functioning living systems. The result was a cell-organism-superorganism coevolution, where each of the three levels of living system was dependent on the other two for its existence.
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Familiar examples of superorganisms from the insect world include ant colonies and bee hives. In the animal world, some apes have assembled into tribe-like structures, but only humans have joined together to form highly-developed superorganisms. Today most humans live within the complex structures of nation-state superorganisms, which meet their complex needs for nourishment, goods, services, work opportunities and protection.
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It is helpful to think of such human-based superorganisms as nation-state-city structures, in recognition of their geographical governance hierarchy. Within this highly-cooperative structure, an individual city or state is not by itself a complete superorganism. Only the collective functional capabilities of a nation, with its states, and their cities, provides the complete array of living system functions that are necessary for interdependent life at the superorganism, organism and cell levels of existence.
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Three Levels of Living System
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Today, human-based living systems exist at three levels, within a structural hierarchy made up of cells, organisms, and superorganisms. Each superorganism typically contains millions of organisms, and each organism contains trillions of cells.
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  Superorganism  
   m i l l i o n s   o f    Organisms   
   m  i  l  l  i  o  n  s        o  f        t  r  i  l  l  i  o  n  s       o  f       Cells   
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Cells are comprised of a myriad of component biomolecules that are harnessed together within organelles, where they carry out the cell's specialized living-system functions.
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Organisms are comprised of a myriad of component cells that are harnessed within organs, where they collectively carry out the organism’s specialized living-system functions.
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Superorganisms are comprised of a myriad of component organisms that are harnessed within organizations, where they carry out the superorganism’s specialized living-system functions.
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This is a recursive structure, where each level of living system (cell, organism and superorganism) has the same basic architectural design. Within this three-level structure, control and initiation of action generally fan-out downward, from superorganism to organisms to cells to biomolecules. The result is a functional action that builds upward, emerging from biomolecule to cell to organism to superorganism. Control goes downward through the hierarchy, while resulting actions start at the bottom and collectively build upward.


Next: Living Systems Structure introduces some conceptual tools that help explain the underlying architecture of living systems.


©1995-2012 Ackley Associates    Last revised: 7/16/11
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